２，４-D丁酯对轮叶马先蒿的防除效果及对草地植被的影响

 为有效灭除草地害草轮叶马先蒿,采用２,４-D 丁酯在巴音布鲁克高寒草地进行了不同时期不同剂量化学防除试验。结果表明,防除轮叶马先蒿的最佳时期为盛花期;最佳药品用量是０．０６６ ｍＬ／ｍ^２;喷施２,４-D 丁酯后,草地植被生态环境得到明显改善,轮叶马先蒿被部分或完全灭除,优良牧草垂穗披碱草在草地群落中占据优势地位,同时杂类草新疆假龙胆受到一定的抑制,草地质量明显提高。     

除草剂2,4-D丁酯对皮燕麦安全性和产量的影响及其残留动态分析

以陇燕3号为试验材料,喷施低、中和高3个剂量(450, 750和1050 mL·hm^-2)的2,4-D丁酯,在药后1,7,14,21,28 d以及开花期、灌浆期植株和收获后籽粒中测定2,4-D丁酯残留量,探讨不同剂量2,4-D丁酯处理对杂草防效、燕麦的安全性、株高和产量的影响。结果表明,2,4-D丁酯对燕麦安全性、产量及田间杂草防效影响显著。高剂量下燕麦出现顶端下垂、叶尖发红和药斑等药害现象。杂草防效随2,4-D丁酯施用剂量的增加而提高。高剂量除草剂喷施后45 d,株防效较药后30 d仍有小幅上升,鲜重防效达到90%以上。3个剂量均使株高有一定程度的降低,高剂量下燕麦株高较对照降低了10.49%。低剂量下干草产量有所降低,但与对照差异不显著(P>0.05),籽粒增产22.64%;中剂量下燕麦干草产量呈增加趋势,籽粒增产40.57%;高剂量下,燕麦干草产量下降了8.85%(P<0.05)。2,4-D丁酯及2,4-D在皮燕麦中的残留量随除草剂施用剂量的增加而上升。施药28 d后,高浓度下燕麦中2,4-D丁酯和2,4-D残留量最高,达0.168 和0.011 mg·kg^-1,显著(P<0.05)高于低浓度处理。综上所述,本试验条件下,750 mL·hm^-2为皮燕麦田2,4-D丁酯的最佳使用剂量。     

In vitro effects of 2,4-dichlorophenoxy acetic acid (2,4-D) on bovine cells.

Bovine fetal muscle cells were exposed to culture media containing 2 mg and 20 mg per liter of 2,4-dichlorophenoxy acetic acid (2,4-D) for varying intervals to determine the in vitro response of mammalian cells to this compound. The concentrations of 2,4-D used were comparable to those used in spray programmes although the residues normally found in pasture are much lower since 2,4-D is rapidly degraded under field conditions. Untreated and treated cultures were analyzed for total cell count, mitotic index and the percentages of differentiating and degenerating cells. The response of cultures to treatment was similar irrespective of the concentrations of 2,4-D used although in higher concentrations there was an initial drop in mitotic index. Other changes noted in treated cultures included an increase in differentiating and degenerating cells compared to those in control. The mitotic cells in treated cultures exhibited unipolar and tripolar spindles and a variety of other abnormalities including malorientation of the mitotic apparatus in relation to the axis of the cell. Myoblasts in initial stages of myogenesis were noted to be in mitosis in treated cultures suggesting that 2,4-D may have a stimulatory effect on myoblasts which in normal myogenesis are in post mitotic stage.     

类胡萝卜素改善水产动物体色研究进展

类胡萝卜素(Carotenoid)对水产动物具有重要生理作用,主要表现在:1 )抗紫外辐射的保护作用;2 )作为受精激素,改善卵质;3)提高免疫,促进生长和成熟;4)增强对高氨和低氧的耐受性;5)作为维生素A的前体;6)水生动物的强抗氧化剂和脂质过氧化反应的抑制剂;7)在生长鱼的肉体和皮肤中沉积,作为产品着色剂,在繁殖季节,成熟的雄鱼将类胡萝卜素集中到皮肤上,形成雄鱼的第二性征———婚姻色,而雌鱼则集中在卵巢,形成幼体的保护色(Snodderly,1 995 ;王业勤,1 997;吕玉华等,1 999;李志琼,2 0 0 1 )。本文主要就类胡萝卜素在改善水产动物体色方面的研究…     

2,4-D对盐藻生物量与物质积累的影响

为了研究2,4-D对杜氏盐藻生物量和物质积累的影响,试验采用向对数生长期的杜氏盐藻(Dunaliella salina)中分别添加浓度为0.01,0.05,0.1,0.5,1,5,10,25,50 mg/L植物激素2,4-D对其进行诱导培养,周期性收集藻细胞,对各阶段藻细胞中细胞密度、β-胡萝卜素、叶绿素、总可溶性蛋白含量进行检测和比较。结果表明:在1个月的诱导期内,用0.1 mg/L 2,4-D处理不但能显著加快藻细胞的分裂速度,而且比对照组的生物量提高了22%,β-胡萝卜素的产量增加了7.8%;但该处理的叶绿素含量、总可溶性蛋白含量与其他处理组及对照组都没有明显的区别。     

Embryo cloning in domestic animals]

The cloning of livestock is performed by the nuclear transfer of early embryonic stages into prepared oocytes in order to obtain a high number of genetic identical animals. As the most important technical steps there are maturation and enucleation of the oocytes, isolation of single blastomeres or karyoplasts of the donor embryo, transfer of the nucleus-containing membrane vesicle under the zona pellucida of the recipient cell, and fusion of the recipient cell and blastomere or karyoplast. Until now, the largest clone which is known exists of seven bulls. The efficiencies of the particular methodical steps have to be improved. More knowledge of the activation of oocytes, nucleus differentiation and availability of determined cell cycle-stages of mitosis is required. The combination of embryo cloning, cryopreservation of embryos and non-surgical embryo transfer is required for basic research and animal breeding.